science – Page 6 – dangermouse.net

Laser day

Today was my visit to the primary school to talk to the older classes about the solar system, and to supervise my Science Club class while we did experiments with laser diffraction. We measured the diffraction patterns of red, blue, and green laser light through double slits, replicating Young’s seminal experiment which established that light had the properties of waves. We ran out of time to do all of the calculations, but very quickly I got a rough figure of 620 nanometres for the wavelength of the red laser (which actually has a wavelength of 632.8 nm, so we got pretty close). Over the next while I’ll refine the measurements and calculate the other wavelengths too.

It was rainy today in Sydney. At least on the coast. It was dry as I drove towards the school, which is near the coast, and as I came down the hill from the plateau to the coastal strip, it began raining, and was really heavy by the time I got to the school. Unfortunately, we need the rain inland, where the dams are for our water supply.

New content today:

Prep for Science Club

Today I did final preparations for Science Club at the school tomorrow. I checked all the lasers, got spare batteries, and copied the dimensions of the slits in the slides to a sheet of paper so I can read them easily during the experiment, rather than having to squint at tiny print. The blue laser is cool, but it’s difficult to see the diffraction patterns after passing through the slits – I suspect because our eyes aren’t nearly as sensitive to blue as they are to green and red. Hopefully it’ll work better in the dark library at the school.

This morning I did some grocery shopping. I do almost all the cooking at home and I like browsing around the vegetables looking for interesting things to cook with. Corn cobs were on special today, so I bought a couple. Not sure what I’ll make with them yet. Probably just boil them up and eat them on the cob, with something else on the side to fill out the meal. I also bought a chicken breast, but that’s for Scully. We don’t really cook meat at home, except on very rare occasions. (I don’t cook it very rare…)

My wife had her Rock School end-of-term concert this afternoon. Normally I attend in person, but today they were live streaming the concert and she was only singing lead on three songs, so I stayed home to get some other things done while watching the stream. I had to clean up a few messy piles of stuff that I’ve had eating up space on the dining table for a while.

For dinner tonight I made pasta with pumpkin, feta, walnuts, and chilli in burnt butter. It’s one of our favourite ways to have pasta – the nuts add a nice crunch which creates the range of textures with the soft pumpkin chunks, creamy feta, and al dente pasta. (Last night I made a frittata with potatoes, broccolini, caramelised leeks with balsamic vinegar and garlic, and of course eggs. It turned out pretty good, I thought. Taking a solid half hour to caramelise the leeks before doing anything else was worth it.)

The other thing I did today was process and upload a few more photos from my trip to Portugal back in May. Going through travel photos always takes a while, since I take a lot of photos! I started going through photos after our arrival in Porto. Porto is built on very hilly terrain:

Here’s the Igreja de Santo Ildefonso, a spectacular church with azulejo tiles on the front edifice.

New content today:

Cleaning and science

Saturday is housecleaning day, and I did more than normal today, with a thorough vacuuming and dusting, which ate up most of the morning. Then I wrote up the results of the pendulum/gravity experiment I did with my primary school Science Club class a couple of weeks ago, in preparation for my next visit on Monday. I made slides to show the kids, and I also wrote it up over on 100 Proofs that the Earth is a Globe.

In the afternoon, my wife and I took Scully out for some exercise. We found a new park to try out, about 10 minutes drive away. We like going to different places, so Scully can explore. She had a good time running around the grass, meeting another dog there, and chasing a brushturkey and some ducks – I think they were Australian wood ducks.

At the park we saw an amazing cubby house that someone had in their back yard for the kids. The yard backed directly onto the park, with no fence, so we had a good view of it.

New content today:

Lasers!

I have lasers! Today I went to Sydney University and borrowed some of thee lab equipment from the Physics labs, for use in my primary school visit on Monday. I assured the lab technician who organised the loan that I wasn’t going to be borrowing stuff frequently, but he was delighted that I was borrowing it, and said I could have equipment whenever I wanted it. He said it was good that I was doing science with school children, and he encouraged me to get them interested in science. So that was good!

He gave me three lasers, one red, one blue, and one green, as well as a selection of slides with single slits, double slits, triple slits, apertures of various shapes, and a transmission diffraction grating. I’ll have to swot up on my interference and diffraction theory over the weekend so I can run the experiment smoothly and get the kids at school to calculate the wavelengths of the three different lasers during the lesson. It should be fun!

I also caught up with my Ph.D. supervisor while visiting the Physics Department. He’s semi-retired now, but still appears to be working virtually full time, both teaching in the labs and doing research into fast radio bursts with the Molonglo Observatory Synthesis Telescope (the telescope I used to do my Physics Honours project back in the day). He’s the author “R. W. Hunstead” on this 2017 discovery paper.

New content today:

Winter blast

Today was cold and windy. It really felt like winter for once. I went out for lunch and the sky even had clouds in it! They were pretty thick and grey in fact, and I thought it might rain, but the promise of any precipitation turned out to be false.

Besides being a very warm winter, it’s also been extremely dry. We’ve had just 3 mm of rainfall so far this August, and Sydney’s average August rainfall is 80.3 mm. In July we had 43 mm of rain, mostly loaded into the first week, while the July average is 95.7 mm. So we’ve basically had 6 weeks with almost no rain at all. The news tonight reported that Sydney’s water supply dam level is now below 50% – the last time this happened was 15 years ago.

Besides the false promise of rain, the weather was pretty wild. I took Scully out to the dog park, and even though I rugged up in a jumper (sweater for the Americans) and a windproof jacket, it was still nastily cold with the wind blowing off the harbour. While there and chatting with some of the other dog owners, we heard a big crack, and we turned to see that a branch had fallen off the huge Moreton Bay fig tree that we were sitting/standing under (there are wooden benches there for sitting, which many of the owners do). Fortunately, it was on the far side of the tree, and didn’t land on any of us or our dogs. It landed on the street beside the park, narrowly missing someone’s parked car (lucky it didn’t land on that too).

A few of us dragged the branch off the street to clear it for traffic, and I took a photo. It’s not a huge branch, but would certainly have caused an injury if it had fallen on someone, or dented the roof or smashed the windscreen of a car. You can see it’s longer than a car, and it was fairly hefty.

That’s Scully on the right, with the red doggy-jumper. Next to her is Monty, a chihuahua-Jack Russell cross. Up on the street is Scout, a west highland white terrier. As you can see, all the dogs are rugged up for the winter weather!

Also today I contacted Sydney University again to arrange to borrow some lasers and diffraction slits for my next visit to the school where I teach my Science Club class. We’re going to measure the wavelengths of different colours of light! I’ll go in tomorrow to pick them up.

New content today:

School science visit

Today was the big day! I spent the day at a local primary school, talking to the kindergarten to Year 2 classes about the solar system. I got back in 2 weeks to do the Year 3 to 6 classes. It’s Science Week, so some of the kids also set up tables in the playground at recess to show off the science experiments they’ve been doing in class recently. There were crystals being grown, model boats being floated and loaded with weights until they sank, electronic kits being used to build various gadgets, and the Science Club showed off some results from the bacteria growing experiment I did with them earlier this year.

Also today I spent an hour and a half with the Science Club students. We went through the results of the colour naming experiment, which I reported on over on 100 Proofs not long ago. Then we performed a new experiment, to measure the strength of Earth’s gravity using a pendulum. We varied the mass of the pendulum, the distance it swung, and the length of the string. We took a whole bunch of measurements, and I’ll analyse them and calculate the results for next time we meet in two weeks.

Oh, and we also made another measurement of the length of a vertical stick’s shadow at midday, as part of our ongoing measurement of the size of the Earth using the geometry of the Earth’s orbit.

It was a busy day, and I didn’t have time for much else other than relaxing afterwards! The teachers at this school work very hard for their students, and I’m constantly amazed how much work they do and how demanding it is. School teachers are one of the most under-appreciated professions, easily.

Chilly Sunday

It feels like a little bit of winter has finally hit Sydney this weekend, with cold weather and strong winds. It was a good day to stay inside, but Scully needed some exercise so we went out for a bit in the afternoon to run around the park. Oh and this morning she had a visit from Luna next door for a play date:

Yes, our neighbour has a black toy poodle too!

Otherwise I continued preparing for tomorrow’s school visit, finishing off my slides on the solar system. And figuring out relative sizes of various balls that I’ll be using to represent planets and the sun and stuff.

Oh, and I’ve been intending to start doing this for a while, but keep forgetting, so let’s start today. New content today:

School prep

Saturday is housecleaning day at Chez DMM. After the weekly chores, I spent much of the day preparing for my school science visit on Monday, putting together slides for my talk on the solar system, and calculating what size balls I need to have ready to show the kids the comparative sizes of the sun and planets. I’m borrowing a 600 mm exercise ball from a friend. If the Earth is that size, I need a 160 mm diameter ball to represent the moon – I think the styrofoam ball I used for this 100 Proofs that the Earth is a Globe post will work nicely. It’s 150 mm, but close enough. And then to show the relativedistance between the Earth and moon I need to put the balls 18 m apart, which I think I can just about manage in the school library where I do my presentations.

And if the sun is represented by the exercise ball, then the Earth needs to be a 5 mm bead, and it needs to be 64 metres away! And Neptune needs to be 19 kilometres away! Hopefully this will impress on the kids just how big space is.

On a different topic, I noticed a disturbing thing today. I made a post to the Irregular Webcomic! Facebook page, and as I was doing it I noticed that Facebook was advertising some groups that it thought I “should join to increase your audience”. What sort of groups were these? Let’s take a look at them:

FOR THE BOYS – a group whose icon is a bunch of bikini models
Over 18 PEEP SHOW – icon is a silhouette of a woman
Holden Haters – icon is a Ford logo
Have a laugh Australia – icon is an “R over 18s” logo

So, Facebook, I’d like to know (a) why do you think people in these groups might be interested in my comics, and (b) why is there no feedback mechanism to let you know that these groups are not appropriate, or to hide them as suggestions?

School science prep

Today I did further preparation for my school science visit on Monday. I’ve been trying to contact a nearby high school to borrow some of their lab equipment, but they kept not returning my calls. So this morning I decided to try Sydney University, where I studied for several years, and know some of the staff in the physics department. I called up and got onto the first year lab coordinator (who I hadn’t met before) and asked her if I could borrow some stuff. She put me onto the lab technician, but he wasn’t in yet, so I sent an email.

Then I was planning to go do some grocery shopping, but I didn’t want to be out driving the car when he phoned back, so instead i stayed home in that sort of anticipatory state that makes it hard to concentrate on anything. He emailed back at 11:00, saying to meet him in the physics labs at 11:45.

Now, I was at home, and the university is on the other side of the harbour… I mailed back saying I might be a few minutes late, and jumped in the car. Fortunately traffic wasn’t bad and I managed to find a parking spot right next to the university gate closest to the physics building, so I was actually on time. I borrowed a retort stand and clamps, and a brass mass carrier with a stack of brass weights. Pretty simple stuff, but it would have been tricky to improvise adequately for Monday.

And I spent some time trying (in vain mostly) to help solve puzzles for the MUMS Puzzle Hunt. I don’t know where the rest of the day went!

Oh! I queued up a bunch of new comic submissions for Lightning Made of Owls. We had a bit of a slump in submissions for a while, but now there are several comics in the queue. If you want to make a simple gag comic and have it published, send it in!

Colour naming

I spent all day today doing science! If you weren’t aware, I do volunteer work with a primary school, going in to teach science stuff to kids from kindergarten to year 6. I talk to all of the kids at the school, but this year I’m also running a Science Club for 13 of the very keen science students, ranging from years 2 to 5.

A couple of months ago I ran a colour naming experiment with them, to explore the psychophysics of what colours we see and deciding what names they should have. I won’t go into gory detail here, because I described the experiment in detail in a previous post over on my science blog, 100 Proofs that the Earth is a Globe. Today I spent all day (about 10 hours of work as I type this) analysing the results and preparing slides to present to the students next time I see them (on Monday next week). Again, I’ve written a detailed post about it over on 100 Proofs. But here’s a sneak preview of the results:

Besides showing the kids the results and talking about them on Monday, we’re going to do another new experiment: measure the acceleration due to Earth’s gravity! I’ll write that up over on 100 Proofs too.